How to install a AGP Graphics Card
Before PCI Express graphics card became dominant, most modern graphics cards were AGP based and connected to the AGP bus of the motherboard. An AGP bus (slot) looks like the following image. The brown slot is where you connect your AGP graphics card.
Place your AGP card on top of the slot and gently push it down. The card should firmly sit into position.
All you need to do now is to screw the metal plate on the front of the card to the ATX case. Use the screws supplied with case and screw the card to the case.